The instant invention relates to a linear interpolation operator, that is, a calculation device permitting, if one considers that a value y is a linear function of x and if one knows the values of y (y.sub.1 and y.sub.2) corresponding to two specific values of x (x.sub.1 and x.sub.2), to calculate the value of y corresponding to any given value of x included within the interval [X.sub.1, x.sub.2 ].
Such a linear interpolation operator is especially implemented in the field of synthesis graphic devices of bi- or tri-dimensional images for line plotting, Gouraud smoothing, Phong smoothing, S-plines, ray tracing and more generally for signal digital processing.
In mathematical form, a linear interpolation is written as follows: EQU y=y.sub.1 +(x-x.sub.1)(y.sub.2 -y.sub.1)/(x.sub.2 -x.sub.1)(1)
On the other hand, the object of the instant invention is to resolve calculations of the type EQU y=(aA+bB)/(a+b) and A*B/C.
According to the prior art, all those calculations require the use of calculation devices, softwares or hardwares, using a computation time period equal to that of about three multiplications (generally, the division duration is substantially equal to that of two multiplications).